#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main() {
    float arr[5];
    float sum = 0.0;
    for (int i = 0; i < 5; i++)
    {
        scanf("%f", &arr[i]);
        sum += arr[i];
    }
    printf("%.2f", sum / 5.0);
    return 0;
}